1. Field of the Invention
The invention relates to a combination of an ethylene-containing polymer with very long chain hydrocarbons containing oil solubilizing groups, said hydrocarbons illustrated by beeswax, ozokerite wax and/or long chain .alpha.-olefins, for improving the cold flow properties of distillate fuel oil.
2. Description of the Prior Art
Kerosene, which is a solvent for wax, has traditionally been a component of distillate fuel oils, e.g. diesel fuels, home heating oils, etc. With the demands for kerosene for use in jet fuels, the amount of kerosene used in distillate fuel oils has decreased over the years. This, in turn, has frequently required the addition of wax crystal modifiers, e.g. pour point depressant additives, to the fuel oil to make up the lack of kerosene.
One class of such pour point depressant additives are ethylene containing polymers. The more effective of these polymers for distillate fuel oil are copolymers of ethylene with other monomers, e.g. copolymers of ethylene and vinyl esters of lower fatty acids such as vinyl acetate (U.S. Pat. No. 3,048,479); copolymers of ethylene and alkyl acrylate (Canadian Pat. No. 676,875); terpolymers of ethylene with vinyl esters and alkyl fumarates (U.S. Pat. No. 3,304,261 and 3,341,309); polymers of ethylene with other lower olefins; etc. Also, homopolymers of ethylene (British Patents No. 848,777 and 993,744) and chlorinated polyethylene (Belgium Pat. No. 707,371) are now known as distillate pour depressants.
Natural occurring materials which have been used as pour point depressants for lubricating oils include beeswax (U.S. Pat. No. 2,107,772) and montan wax (U.S. Patents: 2,107,772; 2,132,355, 2,150,552; 2,158,370; 2,260,994).
Ozokerite is a hydrocarbon wax which has been reported to destroy the macrocrystalline structure of petroleum paraffins upon addition thereto (Kirk-Othmer Encyclopedia of Chemical Technology 2nd Ed. Vol. 22, page 169, Interscience Publishers, New York, N.Y.).
U.S. Pat. No. 3,762,888 teaches improving the cold flow properties of middle distillate fuels with a combination of oil-soluble pour point depressant polymers together with oil-soluble auxilliary, flow improving compounds.